Tite Thíos
by Pansychic27213
Summary: [Underfell AU] A series of moments in Sans's life that would shape him into the monster he is before meeting Frisk. [Minor violence and angst]
**A/N: Okay, so I haven't seen any stories like this for Underfell. I hope you enjoy!**

 **Tite Thíos**

"Papyrus," Gaster called, voice rumbling across the room and filling the air with electricity. "Come here please." The young skeleton hesitantly approached. "Sans, go to your room."

"But, Dad-" the older brother protested anxiously.

" _Now_ , Sans," the scientist snapped. The tiniest skeleton paled and quickly scampered upstairs. The single father took a deep breath before facing his youngest son.

"Have I done something wrong?" Papyrus questioned. If he was nervous, it didn't show.

"No, Papyrus," Gaster sighed. "I think we finally need to have a very _important_ talk."

"Ew, Dad-!"

"Not that!" The lanky monster assured. "It's about... Sans."

"Did Sans do something wrong?" Papyrus asked. Now, he sounded upset. His smaller brother had already taken a beating at school; he couldn't afford to be punished at home too.

"No, Sans isn't in trouble either. I just-" the adult sagged into his seat, burying his face in his hands. "You know how King Asgore is, correct?"

"Yes, but what does that have to do with-"

"Let me finish." Gaster rubbed at his temples. "He is very strict, and he doesn't have much regard for safety. He has me working on a lot of dangerous projects right now, and I... I wanted to make sure you and Sans would be taken care of."

"Do you..." Papyrus gulped. "Do you think something's going to happen to you?"

"I don't know," the father shook his head. "But it's always better to be prepared, in any case." There was silence for a moment. "Papyrus... Your brother is... different. He works differently than other monsters."

"Because he only has one HP?" The child questioned.

"No, he thinks differently," Gaster corrected, tapping the side of his head. "I don't know _why_ , but he still believes there can be _good_ in everyone." The monster shook his head. "You and I know better, right?"

Papyrus nodded.

"In this world, it's kill or be killed," the young skeleton parroted. He paused. "But, Dad, I don't understand. Why are you telling me this?"

"Sans, he's fragile, not just physically, but mentally also. People are going to continue to attack him. It's up to you and I to protect him from that. Maybe one day he'll learn, but until then, we have to keep him safe," Gaster declared, strong and commanding. "Our family is small and poor, but that's okay. We have each other. We just have to look out for each other."

-{[(•)]}-

"C'mon, Sans!" Papyrus yelled. He took another lunge forward. The smaller skeleton yelped and scrambled backwards. "FIGHT me!"

"No!" Sans cried. "I can't! I'm not gunna hurt you!"

"This isn't _about_ hurting him," Gaster called from the sidelines. "This is about strengthening your defensive magic! Both of you!"

"I don't have the _guts_ to do it," Sans somehow managed to quip, while still dodging Papyrus's attacks. The taller skeletons groaned in frustration.

"Just do it, Sans!" The bigger child screamed. "You have to do it eventually!"

"No, I don't!" Sans insisted.

"FIGHT BACK!" The screech was accompanied by a volley of bone attacks. There wasn't any room to dodge. Sans watched the approaching attack with a look of awe and terror.

Gaster threw up his own bones just in time to save his son.

"SANS!" He roared. He marched across the snow, ignoring that both of his children were frozen by what had almost occurred. "Are you really such an idiot to not realize what this is _about_?!" The towering monster shook his smallest son. "You _have_ to learn how to defend yourself! This _isn't_ a real FIGHT! But someday, you _will_ be in one! No one will be able to SAVE you! YOU COULD DIE! YOU ALMOST DIED JUST NOW!"

"I-I-I-" Sans stuttered, wide eyed and trembling.

"Dad," Papyrus sighed. "I don't think this is working..." He averted his eyes and tried hard not to think about how he almost dusted his brother right then. "Maybe we could try something... a little slower?"

Gaster took a deep breath and released the tiny skeleton. He took a moment to compose himself. "What do you suggest?"

Papyrus focused on his brother. "I'm going to throw an attack at you," he warned. "And you have to stop it from hitting you, either with your own bone attack, or just magic."

"O-Okay, but-"

"You don't have to counter-attack at all," Papyrus didn't add the silent ' _yet_ ' that hovered on the air. "Just defend yourself."

"I-I guess..." Sans mumbled. He tugged at one of his sleeves but didn't protest any further.

Papyrus raised a small bone attack and held it in place for a moment. He pushed it forward. Sans gulped but quietly blocked it. Both bone attacks disappeared without a sound. The younger brother's next attack was a little faster, but the smaller still managed to keep up. They kept going like that, getting faster and faster. Gaster had to admit, he was impressed by both of his boys' skills.

-{[(•)]}-

"Dad?" Papyrus called. He adjusted Sans on his back as he peeked into the office.

"What is it-" Gaster turned, then his jaw dropped and he rushed forward. "What happened?!" He cradled his eldest son carefully, checking over his cracked skull and fractured jaw.

"The kids at school," Papyrus whispered, sticking his chin up as he did when he felt unsafe. His eyes were watering, and Gaster patted his shoulder until they dried. "They... They just attacked him... I don't... He defended himself, but he didn't FIGHT back. They... They would have won, but one of the teachers saved him. She let us come home, b-but Dad, is he-"

"He'll be fine," Gaster assured. "Can you find something liquid in the kitchen, with a bit of magic?" Papyrus nodded bravely and scampered off.

"Sans," the adult sighed, trying to heal the cracks and hairline fractures. There just wasn't enough KINDNESS in his soul to do the job. "Silly child. You'll have to FIGHT eventually."

"This is all I could find..." the youngest skeleton scampered in and offered a bottle of mustard with a look up disgust.

"That's fine," Gaster chuckled. He propped Sans up and let the tiniest member of their family drink it up.

-{[(•)]}-

"Sans. Papyrus," Gaster called. His voice pulsed across the house with a deep sense of rage. The boys quickly entered the office, wondering what could be the source of their father's anger.

His back was turned to them; they felt free to openly show their unease.

"The school can't do anything about the attacks. It's a 'constructive environment' for students to 'prepare for the real world.'" He scoffed. "I _hate_ this." His fists clenched, tucked behind his back where the boys could see them. "What has our race become, that even children fight for their lives in a place that was meant to be safe, and educational, and protected?" Purple magic flared around him.

"Dad," Sans frowned, stepping forward. "I'm okay, really! They-"

"It's not ' _okay_ ', Sans!" Gaster spun around, his lanky form towering impressively. "You are weak. Your HP is terrifyingly low. You won't FIGHT! No one, not even those meant to protect you, will step in for you now! You are _going to die_! There will be _nothing_ Papyrus and I can do for you! If you can't fight, at least ACT like you _will_! At this point, it may be the _only_ thing that will SAVE you!"

"D-Dad," Sans pleaded.

"We're going to train more," Gaster snapped. He turned again, this time grabbing papers and scribbling a schedule across them. "You're going to increase your magic levels until you _radiate_ power, until _no one_ will even _approach_ you. You're going to increase your DEFENSE, until it takes multiple hits to even lower your HP by _half_ a point. You're going to practice your attacks, until you can hit a target a hundred _yards_ away in the _dead_ of night!"

"Dad!" Papyrus cried, trying to stop the madness that already had Sans trembling.

"YOU _WILL_ BE SAFE!" Gaster cried and choked on a sob. "YOU CAN'T DIE. I WON'T LOOSE YOU!"

Sans didn't hesitate.

He ran forward, wrapping his tiny arms around his father's waist as much as he could. Tears were running down his own face, and quivering hiccups bubbled up from his rib cage.

"I-I will, I promise," he wept. "I'll train with you. I'll work r-really hard. I swear. I won't d-die, I won't. I love you. I'm s-sorry."

Papyrus wrapped his arms around both of them, sockets closed to hide his own liquid fear.

-{[(•)]}-

"Harder, Sans," Gaster barked. The attacks shattered the tree. "Don't look so excited. Emotion will be perceived as weak."

"I'm trying," Sans frowned.

"Emotion will get you killed," Gaster growled. "Hide it as much as you can. New exercise. From now on, you will practice keeping a straight face in a mirror."

"Aw, c'mon!" Sans shouted. "I'm already training day and night, in the house, in the workshop, at school, out here! Now I gotta train in the _bathroom_ too!"

"I'm doing this to protect you!"

"No one even attacks me anymore! Not since Papyrus started fighting anyone that even _looks_ at me! This is just becoming a waste of time!"

"Don't talk back to me! Again! Aim more to the right! You always veer left!"

"Gimme a break!" Sans snapped. "We've been doing this for _hours_!"

"Do you have any homework?"

"No...?"

"THEN AGAIN!"

-{[(•)]}-

"Lazybones," Papyrus murmured affectionately. He helped Sans pick up their room, separating clean clothes from laundry with his great sense of smell. "You're always so tired nowadays."

"I don't do it on purpose," Sans sighed and sunk deeper into his mattress. "Dad's been working me to the _bone_."

"Ugh, spare me. He's doing it because he cares. Besides, it's good for you," the larger brother reasoned. He folded a couple shirts and placed them in the dresser.

"It's not fair!" Sans threw his hands up. "He's not making you train at three in the morning! He's not monitoring everything you eat! He's not constantly looking over your shoulder! I get it, I gotta stay safe. But this is _insane_!"

"You know what's _insane_ ," Papyrus growled, sharply putting pairs of socks together, "being _ungrateful_. It's a kill or be killed world, and you can't afford to slack off for even a second-"

"You _always_ say that!" Sans yelled. "I get it! The world is _so_ dangerous! But not _everyone_ is out to hurt each other! There _are_ monsters with good in them, and my best examples of that are _you_ and Dad! And it's not 'slacking off'! I just want to get a _full night's sleep!_ "

"I can't _believe_ this!" Papyrus shouted back. "After _all_ this time, _all_ the attacks, you _still_ think anyone would rather SPARE you than _dust_ you?! You're just free EXP!"

The teens breathed heavily, staring at each other as their words took the time to settle in. Papyrus's jaw shut with a near silent _clack_. Sans pulled up his hood and turned his face away.

"Okay. If that's what you really think."

He stood up and began walking.

"Where are you going?" The younger brother whispered, his tone colored with regret.

" _Does it matter?_ "

Sans left.

-{[(•)]}-

"Where have you been?" Gaster demanded. A glimpse of fright passed through his eyes, but it quickly dispersed under his anger.

"Out," Sans muttered. The taller skeleton's head tilted, searching for any trace of emotion.

"Not good enough," the monster declared. "You missed training. C'mon-"

A bone snapped through the ground, stopping barely a centimeter from his throat.

"No," Sans said, blankly. "I'm going to bed. I had my practice for today. You don't have to... ' _worry_ '." His head tilted just show, exposing a bright red iris glowing with powerful magic. Gaster almost choked on the waves of energy permeating the room.

" _Sans_ ," he managed. "What _happened_ to you?"

"Doesn't matter," the teen murmured. His magic emptied from the room like a black hole, and his bone attack dropped back through the floor. His eyes flashed back to white and slipped down to his sneakers. "I'm gunna sleep. And I'll wake up when I'm ready. And I'll eat what I want. I'm gunna be fine, Dad." His teeth shone in a startling smirk. "I'll survive just fine."

-{[(•)]}-

"Dad?" Papyrus knocked on the door frame. Gaster turned around slowly, stretching his back and arms. There were dark circles under his eye sockets.

"What is it, Papyrus? I have to finish these equations for the CORE or Asgore with have my head." He chuckled lowly. He sighed and waved his youngest son into a seat.

"I-I wanted to talk to you," the shorter skeleton started. He kept his face as straight as possible. His chin jutted up in the air. "About the night Sans started acting... different." Gaster's gaze sharpened noticeably.

"What do you know?" He questioned. "Did he say _anything_? Do you know _where_ he went?"

"I-I-" the teen fumbled and broke down. He played with his phalanges, staring down instead of at his father.

"Papyrus," the monster murmur slowly, voice rising in volume as he continued. "What happened that night? What changed between you two?"

"We... had an argument," Papyrus answered. His voice trembled. "He said there had to be more _good_ monsters because... because he'd seen _us_ -"

"Papyrus?"

"And I said it didn't matter because he was just free EXP!" The younger skeleton shouted. He buried his face in his hands, his shoulders shaking painfully.

"Papyrus!" Gaster gasped. Even if they often reminded Sans of his low HP, it was to help him stay cautious and safe. Saying some was _just_ some EXP... It was one of the _worst_ kinds of insults. " _Why_ would you say something like that?"

"It's true!" The teen threw his hands up. "That's what they're all saying, what they all think of him! They leave him alone because of me, but he can't just think he's safe! If I wasn't there, they'd dust him in a heartbeat!"

"Papyrus, that's enough!" Gaster cried. "Sans is much, much more than free EXP! He's _top_ of his class right now, and _that's_ enough to protect him at the moment. And _insulting_ him won't help him in any way." He took a deep breath and looked his son straight in the eye. "You need to _apologize_."

The monsters glared at each for a long moment.

"Alright. I will," Papyrus relented and turned away.

"Good. Do it. Now."

The teen got up and left the room.

He never apologized.

-{[(•)]}-

"Sans!" Gaster yelled in excitement, jogging across the snow. "Look at you! Ah!" He picked his smallest son up and spun him around. "Valedictorian! That was a wonderful speech! I'm so proud of you!"

"G-Gee, Dad," Sans blushed. "You're makin' a scene."

"Oh, I'll make a scene if I want to! And you even took all the courses necessary to become a scientist right out of school!" Gaster cheered. "We need to fill out the forms right away and see about getting you boat pass and..."

"Hey," Papyrus whispered. Sans looked up to him in surprise.

"Pap! You came!" He breathed.

"Yeah. I just wanted to say... I dunno... Good job, I _guess_." The younger brother looked away. Sans tucked his hands in his graduation robe.

"Uh, thanks, I _guess_ ," he muttered back. Papyrus scoffed and stormed away to hang out with his friends. Sans reached out a hesitant hand, but his brother was already gone.

"...and maybe you'll even become my assistant! Oh, wouldn't that be perfect!" Gaster grinned. The tiny skeleton looked up at his father.

"Y-Yeah. That'd be great."

His eyes trailed after Papyrus's distant form.

-{[(•)]}-

"And this is the MAIN LAB," Gaster explained, leading Sans through their shared workspace. "This is where most of the other monsters do their experiments and research. As Royal Scientist, and Royal Assistant, we'll be allowed to oversee any project. Our actual work area is back here."

They moved into a a new part of the lab, much dimmer and more frightening than before.

"Hmm," Gaster frowned. "It seems they haven't replaced the light bulbs yet." He shrugged. "It's fine. None of our experiments are light sensitive anyway."

"What exactly will we be working on?" Sans asked. He pulled at his lab coat, wishing he had more pockets, and fiddled with his name tag.

"We're... experimenting with the human soul."

"What? Really?"

"You know as well as any monster that we need seven human souls to break the barrier. What you may not know, is that five humans have already passed through the Underground and that Asgore plans to declare war on humanity as soon as the barrier is broken."

"No way!" Sans yelped. "That's crazy! Just looking at the exponential rates of growth from when we lived on the surface, we already know that they outnumber us 70 million to one! We would never win."

"Keep your voice down," The larger monster admonished. "I know that, and you know that. But Asgore is unwilling to listen. He's only out for revenge. It would take a _miracle_ to save us from his delusions."

"And scientifically, miracles don't exist," the younger skeleton scowled.

"So, instead," Gaster continued. "We're trying to create artificial human souls. The sooner we break the barrier, the sooner this mess can be resolved. We might even manage it before Asgore looses his last sliver of sanity."

He pushed open a door, revealing a lab of patients and a yellow lizard monster in another white coat.

"This is Dr. Alphys," Gaster introduced. "She's been the one working with me on the artificial human souls. She has studied the properties of the human trait, DETERMINATION."

"H-Hello, Dr. Gaster," the lizard greeted. She nodded her head in a slight bow, eyeing Sans from the corner of her glasses. "Is t-this your new assistant?"

"Yes. Dr. Alphys, this is my son, Sans," Gaster rested his hand on the skeleton's shoulder. She nodded again, acknowledging his protection and power.

"Well!" Gaster clapped, face lit up like very fews times before. "Let's show you what we got and do some science!"

Sans and Alphys grinned.

-{[(•)]}-

"So," Sans began, stirring the pasta noodles. "How's training going?" Papyrus looked up from his homework with one of the scowls that always seemed to mark his face recently. What happened to the happy child he once was?

"Training is fine," he finally answered and returned to his assignment. "Undyne and I are doing well. It's likely we'll both be Royal Guards by the end of the year."

"That's good," the smaller skeleton hummed. He sampled some of the sauce and figured dinner was ready. He was old enough to move out and eat whatever he wanted, at this point, but it was just so much _easier_ to stay home and cook for Papyrus and their dad.

"Dinner's ready!" He slipped some magic in each plate as he began to serve it up. Working in the labs had greatly increased his magic levels, though he might have to get glasses soon due to the poor lighting.

Gaster slipped in, exhausted from working both in the labs and home office. He sank into his usual seat with a deep sigh, but he offered Sans a grateful smile when his plate was set in front of him.

"How are both of you?" The father asked lightly just before filling his mouth with delicious spaghetti. He almost moaned at the taste; homemade meals were _so_ much better than the noodle cups at the lab.

"Great," Sans smiled. "The experiment we're doing right now has me really excited. I'd bounce off the walls if it wouldn't kill me." Gaster laughed, loud and proud.

"And you, Papyrus?"

"Fine," the teen looked over another problems and marked something in orange. "Undyne and I were going to come visit you at the lab soon. She doesn't believe me when I say my dad's the Royal Scientist."

"Alright," Gaster grinned. "Just make sure to follow any safety procedures we tell you about."

-{[(•)]}-

"So, these are the labs," Sans murmured, tone empty. It was better to keep all his emotions at home and private. Alphys sometimes saw him excited or happy when they were doing science together, but she never took advantage since she was usually the same.

Undyne looked around with her trademark glare. She sniffed, recrossed her arms, and shifted her weight to the other foot. She remained unimpressed.

"And back here is where Dr. Gaster and I work," Sans continued. He led her though the back work area. "Hey, Alphys," he peeked into the lizard's lab. "This is my bro's friend Undyne. She's taking a tour."

"O-Oh," Alphys stuttered, face quickly turning red. "It's n-nice to meet you!" Undyne's glare relented and became blank instead. She stepped into the lab and looked around.

"So, what do _you_ do around here?" The guard-in-training questioned. Something about her tone made Sans snicker and quickly back away.

"T-That's classified!"

Sans made his way to the space his shared with his father, where Papyrus was doing more assignments in the corner. Gaster was explaining the wonders of science to his youngest son, but the teen wasn't paying attention.

"Ah, Sans!" Gaster smiled and waved the smallest skeleton in. "Why did Undyne think?"

"She was bored. But a certain yellow lizard caught her attention, and I think said attention is very much returned," the assistant grinned. Papyrus snickered.

"I _knew_ it."

-{[(•)]}-

"SANS!" Papyrus yelled, waking his brother up. "You lazybones! Why do you always sleep so much!"

"Um... It was nighttime?" Sans chuckled.

"That's NO excuse!" The younger brother scowled. "I have training all day, so I think it's only fair if _you_ clean _your_ half of the room!"

"Alright, alright," the smaller skeleton bumbled around, scooping up socks and trash. "See ya tonight."

"YES! I will return very late," Papyrus informed. He hesitated in the doorway. "So please save me some dinner." Sans looked up at him, wondering about the off expression.

"Of course, Pap."

"Then, I'm off!" And the guard-in-training slammed the door behind him.

"Well," Sans tossed a shirt in the laundry basket. "That wasn't weird."

After a few more minutes, the room was clean, and he went downstairs. Gaster was making breakfast, scrambling eggs and buttering toast while cookbooks floated around him.

"What the heck," Sans muttered. "First, Pap; now, Dad?"

"Oh! Good morning, Sans!" The lanky skeleton grinned. He was wearing casual clothes, a white turtleneck and purple pants. His eyes glowed with the first real rest in years, and his smile was softer than it'd been since Sans was a kid. "You'll never believe it!"

"What?" Sans asked, cautious but also excited. This _had_ to be something good; his dad hadn't looked so peaceful for a long time.

"Asgore saw our work, and he gave both of us the day off! We'll be back tomorrow, of course, but for today, we can just relax and enjoy some time together!" Gaster smiled. His entire body shimmered, the happiness of his soul peaking through.

"Dad," Sans gaped. "That's amazing! That's- That's-"

"I know!"

"What are we gunna do? We can do anything! Oh, who am I kidding?! We're gunna do absolutely nothin'!"

"You bet we are!"

-{[(•)]}-

"SANS!" Papyrus yelled, waking his brother up. "You lazybones! Why do you always sleep so much!"

"Um... It was nighttime?" Sans chuckled. Then stopped short.

Woah, deja vu...

"That's NO excuse!" The younger brother scowled. "I have training all day, so I think it's only fair if _you_ clean _your_ half of the room!"

"Uh..." Sans frowned, staring up at him.

"Did you not here what I said, Sans?" Papyrus snapped. "I need to _go_."

"Uh, yeah. I mean, alright, I'll clean up," Sans felt his brow bones pulling together uneasily as he began to wonder what was going on. "S-See you tonight."

"YES! I will return very late," Papyrus informed. He hesitated in the doorway. "So please save me some dinner." Sans looked up at him, feeling anxiety clasp his soul.

"I- Of course, Pap. But-"

"Then, I'm off!" And the guard-in-training slammed the door behind him.

"Well," Sans whispered. "That was... odd." He stumbled around the room, shakily cleaning as much as he could. There might have been a sock or two left laying around, but he needed to see what was happening downstairs.

Gaster stood in from of the stove, plating eggs and toast; his magic gently floated the cookbooks back to their shelves to be put away.

"Oh! Good morning, Sans!" The lanky skeleton grinned. He was wearing casual clothes. "You'll never believe it!"

"What?" Sans breathed, warily.

"Asgore saw our work, and he gave both of us the day off! We'll be back tomorrow, of course, but for today, we can just relax and enjoy some time together!" Gaster smiled. His entire body shimmered.

"Dad," Sans gaped. "Something's wrong-"

"Sans," Gaster dimmed. "This is a good thing. We can finally... do _nothing_." He chuckled.

"I've... I've heard this before," the young skeleton burst. "I... We did nothing yesterday-"

"I wouldn't say that," Gaster laughed. "We were very productive!"

"No, Dad," the smaller male protested. "Yesterday, Pap woke me up and asked me to clean my room, because he was going to be in training all day. He said the _exact_ same thing this morning-"

"Sans," his father sighed. "That's just how Papyrus is-"

"No! Yesterday morning, I came downstairs and you were making breakfast! And we had the day off and we laid on the couch and did nothing!" Sans cried.

"Oh," Gaster worried. He swept over and felt his son's forehead. "Maybe you should take more vacation days. I think the stress is getting to you."

"No! Dad! I can prove it! I can tell you exactly what's going to happen on tv! I can tell you that Papyrus won't be home until after dark, and he'll be angry and won't say anything to us. I can tell you that you're going to make dinner, but you'll confuse the spices! _Dad_ , something's _wrong_!"

And that was how the resets started.

-{[(•)]}-

Sans trudged through the snow a few days later, his lab coat slung over his shoulder. He'd been told to go home early. The 'stress' was 'getting to him.' Time had started progressing normally after a second reset. He didn't know what'd caused them in the first place, and he had frantically checked every experiment in the labs to make sure it wasn't one of them.

Now everyone just thought he was going crazy.

He sighed and massaged the back of the vertebrae in his neck, staring up at the crystals the sparkled in the ceiling of the Underground. The system needed to create day and night was amazing; a series of crystals reflected sunlight through hundreds of tunnels and caverns to deliver it to the monsters.

San tried to decide was he would make for dinner tonight-

"ACK!"

Something crashed into him, and both beings crashed to the ground. Sans rolled up on impact, trying to keep his head from being bashed against the rocks under the snow. It was disorienting, and he was slower to get up.

He caught a glimpse of a yellow striped shirt before the other person started running away.

"Hey, kid!" Sans cried. "Wait!" He stumbled upright and weakly followed after the child. "Stop! Kid!" His legs trembled, head spinning, as he tried to catch up. "I'm not gunna hurt you- ACK." He slipped and fell down again. "Owwwwwww..."

He breathed heavily for a long moment.

He wasn't strong enough for this. He should just go home.

Silently, Sans pushed himself up and weakly made his way to his dropped belongings. Shaking phalanges plucked at his lab coat, trying to pick it up.

Slowly, a hand entered his field of vision, grabbed his coat, and passed it to him. He looked up, and met the anxious eyes of the child.

"Heh, thanks, kid," he smiled as gently as possible. They gathered the rest of his things. "You're a human, aren't you?" The child flinched back and looked panicked. "Hey, I said I wasn't gunna hurt you, right? Well, I'm not. I don't... _do_ that." Sans glanced away, remembering years of training and lessons.

"So, what're you doing in a place like this?"

"I fell," the little boy whispered. He wrapped his arms around himself, looking sad. "I was running from my brothers and I fell into the mountain."

"Aw, man. I'm sorry, kid," Sans offered.

"Everything's so scary here. You're the only monster who's been nice to me..." The kid continued. He plucked at his yellow shirt. The skeleton realized he might be cold and gently wrapped his coat around the smaller being.

"I wouldn't doubt it," Sans mumbled. "A long time ago, we kinda got trapped down here by the humans. After a while, the other monsters started to loose hope. Basically everyone swore they would get revenge. I just... don't see the point." The skeleton shrugged.

"But, hey, you wanna come home with me? I'm making spaghetti."

-{[(•)]}-

"SANS! I, the Great and Terrible Papyrus, am home!" The youngest skeleton called. He hung his coat up by the door and moved into the kitchen. "SANS! _Who_ is this?"

"Huh? Oh, him? Lost kid. Thought I'd give him dinner or somethin'. And you might wanna shorten that intro there, bro. It's a mouthful."

" _Sans_!"

"What?"

"What if he's dangerous?! Do you not think at all?!"

"Hey, I use this big ol' skull of mine all day at the labs. I can afford to be stupid at home."

"NO, YOU CAN'T! _AUGH_! I'm going to my room!"

"You sure you don't want to stay for spaghetti?"

"NO WAY!"

Papyrus stormed upstairs.

Sans grinned at the human, and they removed the hood they had pulled up.

"See, he never even guessed what you were. Now eat up. My dad'll be home soon, and he's not nearly as oblivious. We gotta get you going again."

-{[(•)]}-

"Hey! Papyrus!" Undyne's excited voice came through the door and echoed through the house. "You won't guess what everybody's talking about!"

"What?" Papyrus questioned, brow bone arched. He looked bored, but Sans could see the excited tension in his spine.

"Someone spotted a human around town! If one of us catches them, we'll be a guard for sure!" She cried. Papyrus quickly pulled on his coat and followed her out the door.

"What are we waiting for! Let's go!"

Sans froze.

-{[(•)]}-

"THIS ISN'T RIGHT!" The kid screamed, kicking and flailing. "I HAVEN'T DONE ANYTHING!"

"It doesn't matter," Undyne grinned, victorious. "We need your soul to get revenge on your kind for imprisoning us here!"

"THIS IS WRONG! YOU CAN'T DO THIS!"

" _I already have._ "

"Leave him alone!" Sans cried, weakly running after them. Undyne set a fast pace, one he almost couldn't keep up with. "He's just a kid!"

"He's a _human_!" The fish warrior screamed. "How _dare_ you defend him! After _everything_ they've done to us!"

"It's not his fault! Please! Don't punish him for someone else's mistakes! There's no JUSTICE in that!" The skeleton pleaded.

"Don't speak to me about JUSTICE!" Undyne roared. She threw a few spear attacks at him, which he easily dodged. "I'm taking him to King Asgore, where he'll get all the 'JUSTICE' he deserves!"

She threw up an attack, blocking the road and keeping the skeleton from following them.

"SANS! SANS, HELP ME!" The kid wailed.

"KID!"

Sans threw bones attacks at the spears. They stayed strong. He tried his blasters. The spears didn't break. He called for Undyne once again. But she disappeared down the path.

"KID!"

-{[(•)]}-

"Sans, do you need to go home?" Gaster whispered to him. They stood in front of a glass wall, observing the CORE. Strange energy readings had been received, and Asgore wanted them to focus on those. Seems the King had loosened up slightly since receiving another soul.

"I'm fine, Dad," Sans muttered. He looked away, feeling guilt wash over him like a tidal wave. "I'm an adult. I can work."

"I'm not saying you can't. You just seem... tired," Gaster noted. His voice was thinning with age and pinching with worry. "We can talk about it."

"No, we can't," the assistant murmured. He scribbled down some more information about the CORE. "We need to get someone in there to take a look at it."

"Hmm, that's what I was thinking as well," Gaster sighed. "We'll take these readings back to the lab, and I'll go in tomorrow. I designed it after all; I'm probably the only one who will know what's wrong."

-{[(•)]}-

"Are you sure the suit is on properly?" Sans questioned. He felt drained. He hadn't been able to put effort or focus into much of anything, but he would at least pay attention to his dad's safety.

"Sans, we've been checking this for half an hour," Gaster chuckled. "Everything will be fine." He adjusted the thick, black suit once more. "I'm going in."

He entered the machine and closed the door behind him.

" _Sans, can you hear me?_ "

"Loud and clear," the smaller skeleton answered. "Visual and audio are online. Do you see the camera?"

" _Yes!_ " Gaster gave him a thumbs up, and Sans felt the corner of his mouth pull up.

"Okay. Hook your line up to the railing."

" _Sans_ ," Gaster scoffed. " _That's hardly necessary_."

"Dad," Sans scoffed right back. "It really is. C'mon, at least pretend like your care about safety."

" _I do. But we haven't had any changes in gravitational pull, and I doubt they would just start now_."

"I guess you have a point there," Sans sighed. "Do you see anything the could influence the readings?"

" _Hmmm_." Gaster looked around, walking around the scaffolding. " _Odd. I'm not seeing much of anything. It must be deeper in the mechanics._ "

"Should we turn it off so you can take a look?" The young skeleton asked and switched to another camera so he could see more clearly.

" _And turn off everybody's power?_ " Gaster laughed. " _Hardly_." He shook his head, moving to a panel on the wall. " _The problem can't possibly be that deep in the machine. It had to be something at this level, where everything's less fortified_."

"True," Sans admitted. He spun around in his office chair, then looked over the readings. A slight energy spike, but that was usual whenever someone was taking a look on the inside. He focused back on the other scientist.

" _It looks like there are some wires and piping back here that have been damaged_ ," Gaster noted. " _From the black markings, I would say usual wear and tear from existing in Hotland._ "

"So what do we need to do?" Sans questioned. He grabbed a pad and pen, waiting for instructions.

" _I'm going to need my tool kit and some new parts_ ," Gaster huffed. " _I'm probably the only one that could fix this correctly_."

"Okay," Sans nodded. "You want me to call Alphys and see if she can find the parts you need?"

" _Yes, please. I'll just clean up here and meet you outside_."

Sans took off his headset and put it on the desk. He turned to the landline for the office he was currently in and flipped through the pages, trying to find Alphys. Ab... Af... Ag...

The computer beeped.

Sans glanced up, just as the energy readings began to spike uncontrollably. On camera, the interior of the CORE began to shake.

The skeleton scrambled back to the desk, pushing the headset against his skull.

"Dad! Dad, you gotta get outta there!"

" _I know! But I can't!_ "

"What do you mean you _can't_?" Sans shouted. He frantically typed at the computer. If he could just-

" _I can't leave this open like this! The parts are too damanged; the whole CORE will blow!_ "

"How fast can you get outta there?" The young adult demanded. The entire machine shuddered loud enough for him to hear through the compared the readings with the CORE's current output, trying to see if changing something could help-

" _I only need a minute!_ "

"I can get you that, but you have to get your little skelly butt moving."

Gaster laughed, high and panicked.

Sans's phalanges flew across the keyboard.

The CORE rumbled angrily.

" _Okay! Done! On my way out!_ "

Sans looked up at the screen, watching his father run for the exit. The walkway swung precariously, sending Gaster flying into the railing. He gasped in pain but quickly moved on.

"Dad, the energy-" Sans warned, gripping the sides of the computer screen.

" _I can make it-_ "

The entire CORE pulsed bright and blinding, quaking so hard Sans could feel the aftershocks from office.

He opened his eyes.

The skeleton stared at the screen, eyes wide with shock. The energy readings slowed and faded; the computer stopped beeping. The CORE was still.

Silent tears dripped down his face. He blinked rapidly and wiped them off his cheek bones with the backs of his hands. He stared at the wetness in confusion.

He was crying...?

What had happened...?

He slowly looked up to the screens again. The empty interior of the CORE stared back. His headset slipped off his skull, and he grabbed it just before it hit the ground. He glanced at it, then back to the computers.

A sob leapt from his rib cage and out from between his teeth.

Slowly, he slipped out of his chair, falling to his knees. Uncontrollable sobs shook his entire body, and he didn't know _why_.

His soul pulsed in agony.

-{[(•)]}-

Sans quietly pushed open the door and slid inside the house. The lights were dim, crystal-light shining in through the windows. He maneuvered his way around the couch and found himself standing in the doorway of the kitchen. The short skeleton stared at the cold stove, then the table with only two chairs, and finally the fridge with too few notes and papers stuck to the surface.

He turned slowly and walked up the stairs. He stared at the two doors standing alone in the dark. An empty wall emphasized the space between them. He moved to Papyrus's bedroom and peeked inside. His brother slept peacefully, unaware of the lonely feeling soaking the house.

Sans turned back to the hall and entered his own room. It felt too big, too open, too clean. But wasn't this how it'd always been? Since they moved into the house when... when...?

He closed the door behind him and slunk across the room. His coat landed haphazardly across the floor in front of his closet, and his shoes fell in opposite corners of the room. He dropped on to the bed, still staring into the darkness. He hiccuped once before he laid on his bed and tried to fall asleep.

Staring up at the ceiling, memories of his life came to him on a weak stream of thought. Raising Papyrus. Getting bullied at school and having no one to defend him. Papyrus training him. Their first real argument. His graduation. Becoming Alphys's lab assistant. His 'nothing day' with-

Sans bolted upright. Quickly, he grabbed the nearest piece of paper, some kind of report, and began scribbling out the figure in his mind.

The other skeleton was tall, always towering like a living skyscraper. He- He was thin, with long limbs and a smooth face. His skull was cracked, reaching out from his eye sockets...

"G," Sans breathed. "His name... G... I-It starts with... There's a-" He hurriedly put a G on the corner of the page.

The figure in his mind was wearing a thick, black robe, but... but that didn't feel _right_...

He drew the robe, but he found himself adding the top of a white turtleneck. His hand started to fill in him and Papyrus, standing beside the mysterious monster.

The image began to fade from his mind's eye.

"No! NO!" He shouted, hitting the sides of his skull. "Don't- Don't forget! DON'T FORGET! DAD-!" He flipped the paper over, trying to write down everything he could. He ended up simply writing 'dont forget' across the page.

He wept breathlessly, hunched over his desk in the dark.

-{[(•)]}-

"Honestly, I think it's time for me to resign," Sans muttered into the phone tucked between his shoulder and the side of his skull. He sat on the couch, folding clean laundry and creating piles.

"What?! W-Why?" Alphys demanded. He could hear her shuffling around in the lab, probably checking on the DETERMINATION trial patients.

"I just think it's time," he sighed. "I can't be your assistant forever, you know. And... Something's been off with the lab. You feel it too, I _know_ you do."

"It feels... I-I don't know what it feels, b-but that's not a good enough reason to q-quit!" She insisted.

"I can't do it anymore, Alph," he murmured. "It's draining me. Even if I didn't resign, I would still take some time off, and Asgore would never allow that. I think it's better if I just change jobs altogether."

"H-How is it _better_?!" She barked. "You love science! What else c-could you possibly do?"

"Maybe I'll join my brother in the guard," the skeleton shrugged. "It would be an interesting change of pace, at least."

"You want to be one of those- those _mindless_ guards?" She scoffed.

"Undyne's a guard," he reminded with a smirk. "Head of the Snowdin division at the moment, actually."

"S-s-so!" Alphys cried. "I-It's not like I-I care!" He chuckled.

"Whatever you say, Alph." He sobered again. "I just... I _can't_ go back to the lab. I'm sorry, and I don't expect you to understand. This is my official resignation."

"O-Okay, Sans. If this is w-what you want," she sighed. "We're going to m-miss you, you know?

"Thanks, Alph."

-{[(•)]}-

" _You_ want to be in the Royal Guard," Undyne frowned, staring at him from across her desk. The skeleton sighed and sat up straighter.

"Sure. You don't have to make me Captain or anything, but I'd... appreciate the change of pace," he offered.

"What? After the crap you pulled the last time I saw you? When you tried to help a _human_ , and could barely keep up to me at normal _walking_ pace?" She sneered.

"It's been years since then. Some... things have changed," he sighed. He looked up at her. "Look, I can FIGHT. And I'm willing to sit around all day watching for any suspicious crap. I can manage puzzles just as well, if not better than Papyrus, and my knowledge about the human soul could be invaluable in a battle."

The monsters stared at each other, judging and considering.

"Alright."

Sans jolted. "Just like that?"

"Why not?!" She threw her hands up. "Alphys told me about what you did, you know. I may not like or trust you, but your abilities can still be useful."

He nodded.

"But, just know," she leaned forward, looming with an endless shadow. "If you move one _millimeter_ out of line, I will _dust_ you without hesitation." Her eyes flashed dangerously, and he nodded once more, blankly.

"You'll be a lower sentry," she informed, dropping back into her seat. "You can work the station just outside the Ruins."

"Okay."

"Here's your work schedule for the first month. If you're not dust by then, come see me."

-{[(•)]}-

"Hey, _boss_ ," Sans grinned, putting his brother's breakfast on the table.

"Don't call me that," Papyrus snapped.

"Oh, but you _are_ my boss," the smaller skeleton snickered. "Anything I should do today, sir? Can I get you a coffee?"

"Yeah, you can," Papyrus smirked.

"You're smiling."

"I'm smirking. And I hate it."

Sans laughed and went to make a cup. Papyrus stared at his back, a hint of sadness creeping into his eyes. His older brother hardly laughed anymore; he was always sad and quiet. Papryus may be bad at showing it, especially in the past couple years, but he _did_ care about Sans.

He had to take care of Sans because he... thought differently. Who had said that? Someone had told him that-

Papyrus shook his head. He had toughened up in recent years due to his guard training, and he had trouble expressing any 'weak' emotions now more than ever. But they were there- anxiety, concern, _love_.

He missed how his brother used to smile all the time and ramble about science and crack jokes with... and talk to him about the stars and history and other interesting things. They weren't as close since their big argument as teenagers, but they still lived together and that had to count for something, right?

Maybe, with Sans in the guard with him, they could fix their relationship and work together instead of constantly clashing against each other.

-{[(•)]}-

"So... I guess this is your station," Papyrus muttered.

The two skeletons stood in the snow, staring at a little, run-down shack of a guard station. The roof was caving in on one side, and the entire structure was covered in graffiti.

"Nice," Sans mumbled. He stepped forward and used his magic to remove the snow. He lifted the roof into position and propped it in place with a nearby branch. A quick sweep with a bone attack scraped the layers of paint off the sides of the station. "Heh. Feels like home already."

"I should... get to my own shift then?" Papyrus murmured. "I'll be within ear-shot. If anything happens, just scream."

Sans scoffed. "I can FIGHT, ya know."

"Yes," Papyrus agreed. "But you won't." He turned on his heel, scarf waving wildly behind him, and stormed off.

Sans sighed and moved around to sit in his station. He pulled his black sweatshirt tighter around him; he turned up the collar against the cold. His gold tooth made his jaw ache, and he rubbed at it thoughtfully. He remembered getting it when he was little, his jaw cracked open by bullies and his tooth lost forever.

Footsteps crunched through the snow nearby.

He looked up in surprise, and his eyes widened at the trio of approaching monsters.

Speak of the devil...

"Hey, fellas," the skeleton kicked his feet up, lounging even as his soul pumped wildly in his chest.

"Heard ya got in the guard," the orange one declared. He elbowed his buddies, snickering. "Didn't think ya had it in ya, pipsqueak."

It took monumental effort to not roll his eyes.

"Yeah," Sans shrugged. "Thought joining wouldn't exactly be a bad career choice."

"Eh, I wouldn't say that," the purple one smirked. "Seems like this is just one mistake too many. You might need another _lesson_ to freshen you up."

"We're not _kids_ anymore," Sans finally snapped. "Grow up and get a _life_."

The grey one stepped forward, growling. The world tilted precariously and shifted into black and white.

The FIGHT had begun.

Sans waited, watching for what the others would do. The orange one threw a series of attacks, and the skeleton dodged them easily. He considered his options for a moment, then checked each of their stats. The purple one tried to blast him, while the grey one ran around to his back.

They had him surrounded.

He huffed and threw his hand up, sending a slew up bone attacks at the grey one, and threw his other hand to the side, grabbing the orange's ones soul and tossing him.

The three monsters retaliated with as many attacks as they could manage. He barely managed to move out of the way. Luckily, their attacks hit the others opposite from them. They cried out in pain, HP lowering rapidly.

"You guys can back out now, no hard feelings," Sans offered.

"YOU WISH!" The orange one screamed and darted forward. Sans slipped to the side, then ducked under an attack from the purple one. He didn't see the grey one coming from behind.

The skeleton screamed out in pain, feeling his health cut by half.

"I, the Terrible Papyrus, heard fighting!" His brother suddenly charged in, his chin high in the air. "You three! You should not be here, much less _daring_ to attack one of the Royal Guard!"

"You aren't real guards!" The orange one shrieked. "You're just Undyne's personal jokes!"

Papyrus blasted him before he could open his mouth again.

"You really think your brother there is a guard?!" The grey one roared. "He's free EXP!"

" _NO_! HE ISN'T!" Papyrus defended, at the top of his lungs. He threw up his entire arm, send a volley of bones through the ground. The grey monster had no time to dodge.

"PAP!" Sans cried. The grey one laughed hysterically, stumbling forward in an attempt to hit him. The orange one also ran for Papyrus, while the purple monster sent attacks at both of them.

Attention pulled between attacks, Sans threw out a blast to protect his brother and a wall of bones behind him. Papyrus threw out bone attacks at each of the monsters, howling in rage.

Piles of dust dropped to the ground. Specks of it floated on the wind, carried away easily.

Sans stared at the scene with wide eyes. Papyrus was frozen in place, his hand still extended.

"Papyrus-" Sans choked. "I- You- We-"

"Not a word." The skeleton's face darkened. "Nothing happened."

"Nothing _happened_?!" Sans screeched, shaking from his stupor. "You just _dusted_ three monsters!"

"Forget this ever happened!" Papyrus ordered. He pulled himself to his full height. His chin slowly lowered. "They attacked you. It's kill or be killed. And that's all." His eyes were dark with horror and guilt, but everything about him screamed pride and danger.

And something in Papyrus shifted and clicked.

That was all.

 **A/N: So this fic is supposed to end just a little bit before the game would start. Sans slowly sinks into depression and anxiety, Papyrus forces his way into the guard and becomes cold, and both brothers are prepared to kill any monster that crosses them. Then Frisk, a little bundle of sunshine, comes into their life, and Sans finally thinks he can have a chance at redemption for all his past mistakes.**

 **QUESTION OF THE UPDATE: If you could cosplay for ONE fandom for the REST OF YOUR LIFE, but it was THE BEST cosplay EVER, what would you cosplay? I would go with... Um... I dunno, Princess Tutu? It's a really good anime, and they have a lot of really beautiful characters to choose from.**


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